[Ce³⁺-O_V-Ce⁴⁺] Located Surface-Distributed Sheet Cu-Zn-Ce Catalysts for Methanol Production by CO₂ Hydrogenation

Area of Science:

• Catalysis
• Materials Science
• Surface Chemistry

Background:

• Metal-support interactions are vital for copper-based catalysts.
• The role of the support metal's intrinsic properties in catalyst design is often neglected.

Purpose of the Study:

• To design a novel Cu-Zn-Ce catalyst incorporating specific surface cerium-oxygen vacancy species.
• To investigate the influence of cerium on oxygen vacancy formation and its impact on catalytic performance.

Main Methods:

• Sol-gel method for catalyst synthesis.
• Electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) for characterizing oxygen vacancies and cerium states.
• Inductively coupled plasma mass spectrometry (ICP-MS), SEM-mapping, and temperature-programmed desorption of CO2 (CO2-TPD) for surface analysis and adsorption studies.
• Density functional theory (DFT) calculations to understand adsorption mechanisms.

Main Results:

• A sheet Cu-Zn-Ce catalyst with surface [Ce³⁺-O_V-Ce⁴⁺] species was successfully synthesized using the sol-gel method.
• Cerium intrinsically induces the formation of [Ce³⁺-O_V-Ce⁴⁺] on the catalyst surface, confirmed by EPR, XPS, ICP-MS, and SEM-mapping.
• The [Ce³⁺-O_V-Ce⁴⁺] sites significantly enhanced CO2 adsorption, as evidenced by CO2-TPD and DFT calculations.
• Methanol selectivity increased by 10% compared to a catalyst prepared via coprecipitation.

Conclusions:

• The presence of surface [Ce³⁺-O_V-Ce⁴⁺] species, induced by cerium, is key to improved CO2 adsorption and methanol selectivity in Cu-Zn-Ce catalysts.
• Tailoring the support metal's properties, specifically cerium's role in creating oxygen vacancies, offers a promising strategy for enhancing catalyst performance.
• The sol-gel method provides an effective route for designing catalysts with targeted surface functionalities for CO2 conversion.